1. Field of the Invention
The invention relates to a lamp ballast system that can provide a stable operating current to a lamp load.
2. Description of the Related Art
In a conventional lamp ballast system, the operating current that is provided to a lamp load generally fluctuates according to the characteristics of an alternating current (AC) power input. The fluctuation as such can lead to inefficient power consumption and in a shorter service life for the lamp load and electrical components of the lamp ballast system.
Therefore, the main object of the present invention is to provide a lamp ballast system that can supply a stable operating current to a lamp load even under the presence of input power fluctuations.
Another object of the present invention is to provide a lamp ballast system that can automatically cut-off current supply to the lamp load upon detection of load over-voltage conditions.
According to the present invention, a lamp ballast system is adapted to be connected to a lamp load, and comprises a rectifying and filtering unit, a voltage multiplying unit, a frequency inverter unit, and a phase correction unit. The rectifying and filtering unit is adapted to rectify and filter an alternating current input so as to generate a direct current output. The voltage multiplying unit is connected to the rectifying and filtering unit so as to receive the direct current output therefrom. The voltage multiplying unit is operable so as to generate a voltage-multiplied direct current output. The frequency inverter unit includes a driver circuit, an oscillator circuit, and a converter circuit. The driver circuit is connected to the voltage multiplying unit so as to receive the voltage-multiplied direct current output therefrom. The oscillator circuit is connected to and is driven by the driver circuit so as to generate a high-frequency oscillating current output. The converter circuit is connected to the oscillator circuit so as to receive the high-frequency oscillating current output. The converter circuit is operable so as to convert the oscillating current output Minot a stable high voltage, high frequency alternating current output. The phase correction unit is adapted to interconnect the converter circuit and the lamp load, and includes at least one set of a transformer and a capacitor that are connected in series.
Preferably, an over-voltage protection unit is connected to the phase correction unit, the voltage multiplying unit and the driver circuit. The over-voltage protection unit inhibits operation of the voltage multiplying unit and the driver circuit upon detection of an over-voltage condition at the phase correction unit.